A baby may have been flushed of HIV. Is the end of AIDS near?

When the expectant Mississippi mother, already in labor, arrived at the University of Mississippi Medical Center in 2010, she had no idea she would be making history. She had no prenatal care during her pregnancy and had no idea that she was HIV positive, much less that she could pass the virus to her child.

Because she had not taken advantage of prenatal drug therapies that can cut the risk of passing the infection from mothers to newborns from 25% to less than 2%, her doctor took a chance. She started the infant on potent antiretroviral medications (ARVs) that have been...